Flavored tobacco products are cheap, sweet, and appealing to youth. The Federal Smoking Prevention and Tobacco Control Act banned flavored cigarettes other than menthol in 2009, but little cigars and cigarillos (referred to as small cigar) are still sold in a variety of fruit, sweet, and alcohol/cocktail flavors. Electronic cigarettes ar sold in more than 7,500 flavors, including Juicy Peach, Very Vanilla, and Tutti Frutti Gumballs. In addition, retail marketing of small cigars and e-cigarettes as low-cost alternatives to cigarette smoking likely contributes to their growing popularity among adolescents. This proposal seeks continued funding to better understand the impact of retail tobacco marketing on adolescent tobacco use, with a change in focus from studying cigarettes to cigarette substitutes/complements. Specifically, this longitudinal study aims to: (1) test whether adolescents' exposure to retail marketing for flavored small cigars and e-cigarettes is associated with higher odds of past-month and ever use of these products at two timepoints; (2) examine how promotion and price of flavored small cigars and e-cigarettes change over time and as a function of student demography at nearby schools and the proportion of school-age residents in the neighborhood; (3) characterize the strength of local tobacco retailer licensing and test whether stronger licensing predicts higher prices for flavored products; and (4) disseminate research results to federal, state and local stakeholders concerned with regulating tobacco products and marketing. To accomplish these aims, data about adolescents' use of small cigars and e- cigarettes will be obtained from the California Student Tobacco Survey (CSTS), a biennial surveillance survey conducted for the California Tobacco Control Program (in academic years 2015-16 and 2017-18). Each administration of the CSTS will yield responses from approximately 25,000 students (grades 6-12) attending 140 schools that are stratified by region. In conjunction with the CSTS surveys, trained observers will assess the availability, placement, promotion and price of flavored small cigars and e-cigarettes in a random sample of 500 licensed tobacco retailers within walking distance of the surveyed schools. The proximity of tobacco retailers to schools will be determined using a GIS dataset of campus boundary files that better reflects the school environment than previous methods. Multilevel modeling will test whether greater promotion and lower prices of flavored small cigars and e-cigarettes is associated with higher odds of current and ever use by students at nearby schools, adjusting for both individual-level characteristics and school-level demographics. The proposed research would inform tobacco control policy and regulatory science by advancing our understanding of the health risks associated with the retail availability and promotion of flavored tobacco products near schools.